Improving the performance of a heat pipe evacuated solar water collector using a magnetic NiFe2O4/water nanofluid

Abstract

In the recent years, heat pipe evacuated tube solar collectors (HP-ETSCs) are widely utilized due to their easy maintenance and high efficiency. However, increasing the performance of available systems is an important issue that investigated in many studies. The main goal of this study is improving the thermal performance of a HPETSC by replacing the working fluid of the system with magnetic nanofluid. In this context, magnetic type NiFe2O4/water nanofluid has been utilized as working fluid in a HP-ETSC to improve the overall performance of the system. Accordingly, NiFe2O4 nanoparticles has been mixed with distilled water at the ratio of 2 wt% in order to obtain magnetic nanofluid. The performance tests have been performed at various water flow rates (0.016 kg/ s, 0.033 kg/s, and 0.050 kg/s) using distilled water and NiFe2O4/water magnetic nanofluid. The general outcomes of this work indicated positive results of using NiFe2O4/water magnetic nanofluid on the efficiency of the HP-ETSC. Utilizing NiFe2O4/water nanofluid in the HP-ETSC as working fluid averagely increased the thermal performance as 37.72%, 39.59% and 44.96% at flow rates of 0.016 kg/s, 0.033 kg/s and 0.050 kg/s, respectively. In addition, using NiFe2O4/water magnetic nanofluid in the HP-ETSC averagely increased the exergy efficiency as 60.59%, 55.61%, 59.61% at flow rates of 0.016, 0.033 and 0.050 kg/s, respectively.